<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    var a = 10;
    var b = a--;
    //b = a
    // a = a - 1;

    console.log(b);
    console.log(a);

    var c = 20;
    var d = --c;
    //c = c =1
    //d = c;
    console.log(c);
    console.log(d);
</script>
</body>
</html>